Technology relating to handheld flashlights incorporating a direct current power supply in the form of replaceable batteries and low voltage, incandescent bulbs achieved a technological plateau in the 1970's. Advances in the state of the art typically related to methods of packaging the batteries and bulbs, and reflector designs. In particular, the capabilities of flashlights of this type are strictly limited by inherent characteristics of the incandescent bulb itself. Initially, evacuated bulbs using tungsten filaments enabled power supplies in the range of 1.3V (and more when such batteries are connected in series) to provide varying levels of illumination. So-called halogen bulbs permitted higher filament temperatures increasing the output of such flashlights. Nevertheless, the inherent inefficiency of incandescent bulbs limited the duration of operation of such flashlights to a matter of a few hours or less depending on the number of dry cells provided in the power supply. That is, for increased run time the batteries could be connected in parallel. For increased light intensity the batteries could be connected in series (for increased voltage) but at the expense of run time. In addition, filament bulbs are highly susceptible to mechanical shock, breaking the filament and rendering the flashlight inoperative. In addition, substantial development effort was directed to switch mechanisms for intermittently connecting the direct current power supply to the incandescent bulb so as to render either a more reliable or inexpensive switch, or both.
The assignee of the present invention has significantly developed the state of the art with respect to handheld, battery-operated flashlights and personal lighting devices. One example of the advancements made by the assignee of the present invention is disclosed in U.S. Pat. No. 6,953,260 titled, CONVERTIBLE FLASHLIGHT-HEADLAMP issued on Oct. 11, 2005 the disclosure of which is incorporated herein by reference. That patent discloses a convertible flashlight-headlamp employing a plurality of light-emitting diode semiconductor devices (hereinafter “LEDs”). The LEDs are driven by a microprocessor control unit 154 shown in FIG. 7 of that patent. Further details with respect to the circuitry for driving the convertible flashlight-headlamp shown in the '260 patent is disclosed in U.S. Pat. No. 7,015,054 titled, LIGHT EMITTING DIODE DRIVER CIRCUIT METHOD issued on Mar. 21, 2006 to the assignee of the present invention, the disclosure which is incorporated herein by reference. The method and apparatus disclosed therein provides a sophisticated methodology for driving LEDs with a battery supply voltage below the forward bias voltage of the diode or diode array in use with the circuitry. Being driven by a microprocessor-like device (a microcontroller), the flashlight-headlamp is controlled by momentary contact, multi-function switches. Switches of this type are inexpensive and user friendly in that the momentary depression of a control switch (such as switch 58 in FIG. 3 and FIG. 7 of the '654 patent) cycles the logical control unit through a variety of different modes of flashlight operation (e.g., full power, reduced power, flashing, S.O.S., etc.) The circuitry disclosed in the '260 and '654 patents is also used in other flashlights sold by the assignee herein using a single discoid-type battery, and a single LED in a compact package. However, all the commercial embodiments of flashlights produced by the assignee of the present invention rely on a use of a momentary contact switch which is well adapted for computer control purposes.
In 1984, the Mag Instrument, Inc. introduced a small AA battery flashlight, the Mini Maglite® to the public. That flashlight employed a high quality machined aluminum case incorporating a vented waterproof seal system and a high intensity XENON incandescent bulb as shown in U.S. Pat. No. 5,349,506 titled, MINIATURE FLASHLIGHT issued to Maglica on Sep. 20, 1994. FIG. 1 herein illustrates that prior art flashlight design. Referring to FIG. 1, a miniature flashlight in accordance with the Maglica '506 patent is illustrated in perspective, generally at reference numeral 20. The miniature flashlight 20 is comprised of a generally right circular cylinder, or barrel 21, forming a battery housing and enclosed at a first end by a tail cap 22 and having a head assembly 23 enclosing a second end thereof. The head assembly comprises a head 24 to which is affixed a face or lens retainer cap 25 which retains a lens 26. The head assembly 23 has a diameter greater than that of the barrel 21 and is adapted to pass externally over the exterior of the barrel 21. The barrel 21 may provide a machined handle surface 27 along its axial extent. The tail cap 22 may be configured to include provision for attaching a handling lanyard through a hole 28 in a tab 29 formed therein.
The flashlight described in the '506 prior art patent employs a head assembly 23 which operates a rotary switch mechanism. That is, the flashlight 20 of FIG. 1 encloses two 1.5 volt AA batteries in series with an electrical circuit including a miniature bi-pin lamp bulb 45, the aforementioned batteries, and the barrel 21 as part of the electrical circuit. By rotating the head assembly 23 with respect to the barrel 21, a single pole, single throw electrical switch is opened or closed depending on the direction of rotation. Unfortunately, this type of switch is not directly compatible with the advanced LED circuitry disclosed in the '654 patent to Kuhlmann et al. and the '260 patent to Allen. Nevertheless, those of ordinary skill in the art have recognized the mechanical advantages of the Maglite® flashlight 20 design shown in FIG. 1 as well as the inherent advantages of LED lighting systems with respect to incandescent bulb technology. Therefore, at least one manufacturer operating under the trade name Opalec Innovative Electronics, 7097 Terra Bella Drive, Walnut Creek, Calif., 94596 has provided a multi LED replacement module for use with the Maglite® AA flashlight. The module replaces both the reflector, incandescent bulb and so-called switch assembly (mounting assembly for the incandescent bulb) contained between the head assembly 23 and barrel 21. The resulting modified flashlight otherwise uses all of the original case parts, and batteries of the stock flashlight. The replacement module uses three LEDs to provide a minimally acceptable luminosity and only provides one mode of operation—full power.
Thus, a need exists for an LED retrofit module which provides a multiplicity of modes of operation.
A further need exists for a retrofit LED module for use with a flashlight having a rotary single pole, single throw switch.
A further need exists for an LED replacement module for a maglite-type flashlight capable of driving a high power LED replacement module safely.